[Exploit] Can drop through a block/floor using minecart.

You can drop through a 1 block high floor by pushing a minecart off a track then jumping in, using a bow to break the minecart after which you fall through the floor. Both in survival and creative. Only tested in 1.6.2. Would be bad on PVP servers. Video below.

http://youtu.be/To2nscqG_Kw

Recreate:
1. Place track on the floor that has 2 spaces empty below it.
2. Push cart of the track
3. Destroy the track.
4. Get in minecart
5. Destroy minecart with bow and arrow.